Helen Frankenthaler's pieces, above, were groundbreaking in that she used an unprimed surface; allowing the paint to saturate the canvas and it's viscosity to help determine it's presence on the piece. She was a member of the abstract expressionists and influenced the stained canvas work of the color field painters.
Dona Nelson received rave reviews for her paintings that share the stained unprimed canvas as Frankenthaler's work but with the addition of composing both the front and reverse of the stretched canvas. Her pieces are then displayed free standing in the gallery, liberating the painting from the gallery wall.
Dona Nelson's current work continues to utilize both sides of the canvas but she's adding more collage and thread to the piece. I'm especially fond of her pieces that include figures. The application of the people on one side or another adds a depth and focus to the story between them. Raising questions of their relationship and existence in the space.